17mm Blog : Blog

« Looking Back | Main | And it ended with a... »

Using GND Filters on a Digital Camera: Part 3

Posted Wednesday, 17 December 2008 by Sven Seebeck

In the previous two posts on using the GND filters, I wrote about what is needed, what they look like and how they are actually attached to the lens. In this post I will try to explain how they are actually used.

So, let's have a look at my image "Being There" first and I then try to explain what I did there.

I took this image just before sunset with the last bit of the sun still being around the horizon. The dynamic range of the scene was naturally rather big and as almost always I used my filters to hold back the exposure on the sky. But how to decide, which filters to use? Here comes in the metering.

How to meter the scene?

Of course the more you work with filters, the more you get a feeling which filters to use. When I'm in a hurry I start off immediately with a 2 or 3 stop filter and then check the histogram. But to be precise it's still best though to do a quick meter reading. Since I have no external lightmeter yet, I proceed like this:

I switch to "Center Weighted" metering mode and set the camera to TV mode (not sure right now what's that on Nikon right now, I think S)
Then I point the camera/lens to the darker part of the scene (usually the foreground) and adjust the shutter speed so, that it equals for example f4. I prefer to set it to f4 since from there it's at least for me easier to count the f-stops (4; 5.6; 8;11;16;22).
Then I point the camera to the brighter part of the scene (usually, and in this case the sky) and count the difference in stops compared to f4 and there you go. If the camera now shows now for example f16, there is a difference of 4 stops. So a four stop filter should be best to use. Of course I could do the same in AV-mode but in that case the shutter speed and not the aperture is changing, and that somehow is too much math for me ;-)

After that I switch back to AV or M mode and attach the filters and frame the shot. When I then take the image, I usually switch back to Evaluation Metering mode, and most of the time that works fine. In case of doubt, I do a meter reading from the foreground before attaching the filters and shoot manual then.

Where to place which filters:

Which filters to choose is a little dependent on the scene. A scene with an uneven horizon, such as mountains or hills, tree tops etc. ideally requires graduated soft filters, whereas a straight horizon, like in this example, it's better to use GND hard filters. (If these doesn't mean anything to you, please check back on my previous post here).

Application in practice:

In this particular image I used two GND hard filters with together 5 stops to compensate for the bright sky (Disclaimer: I took this image quiet a while ago but I think it was something like this) and moved them down around to the horizon, then focused manually (I usually do), checked the DOF preview and took the shot. Checked the histogram and bracketed a little and took another image. And that's it.

I tried to demonstrate how I place the filter in the following image:

On my way home I already knew there was a nice image waiting for me on the memory card, which is a very good feeling to have.

Of course the filters don't have to be placed horizontally like in this image. On the image "Autumn Rocks" I placed a GND soft filter diagonally across the frame like you can see in the following image:

Resume

With filters it is possible to achieve amazing results and to get the shot in the camera, which is something that I prefer. There are of course situations where it's more useful to blend multiple exposures together in Photoshop, or do a HDR. But for me, the use filters has improved my photography a lot. I will definitely invest in some more filters. This time though ND filters. But I think that should then complete my set.

If you have any questions or comments about these posts, feel free to leave a not in the comments.